The following is a highly idiosyncractic list of books that remind me in some way of The Lord of the Rings or the re-read project.
We’ll start gently, with two critical works and one explicitly “inspired by”:
Tom Shippey’s The Road to Middle-earth examines how Tolkien’s deep attachment to philology (the comparitive study of languages to understand their evolution) is the foundation of his fiction. It’s excellent for both close readings and broad syntheses of Tolkien’s work, though it begins a little slowly.
Ursula K. Le Guin’s collection The Wave in the Mind contains the essay “Rhythmic Pattern in The Lord of the Rings”, which was hugely influential on my re-reading.
And Martin Greenberg and Jane Yolen edited an anthology After the King, containing short stories inspired by Tolkien, many of which are very fine.
And now for the truly idiosyncratic stuff.
If you like Tolkien’s languages, try The Power of Babel: A Natural History of Language, by John McWhorter, which is a lively, discursive, readable look at how actual languages change.
If you like the travel bits and the concern for the environment, try Bill Bryson’s A Walk in the Woods: Rediscovering America on the Appalachian Trail, which is environmentally-minded travel through forests, but first-person and funny.
If you like Middle-earth for its epic scope and mythological resonance, but would appreciate more women characters, try Guy Gavriel Kay’s Fionavar Tapestry, which was written after Kay assisted with the compiling of The Silmarillion and is very much in dialogue with Tolkien’s works.
(Also worth noting are Kay’s later non-epic fantasies, for their deep concern with civilization, art, history, and what must be done to keep and defend them. I like the Sarantine Mosaic duology and Tigana, which are inspired to closer or looser degrees by historical situations in our own world.)
If you like Middle-earth for its epic scope and mythological resonance, but would appreciate something not based on Northern Europe, try Journey to the West by Wu Cheng’en, a 16th century Chinese epic quest novel that is funny, fantastic, adventurous, and philosophical. The Anthony C. Yu translation has many notes to give the present-day reader context; the W.J.F. Jenner translation is more fun.
Honorable mention to David Anthony Durham’s Acacia, which is the start of a epic fantasy series based around a Mediterranean-like kingdom and featuring a multi-ethnic, multi-racial world. (It’s only an honorable mention because I’ve just started reading it, but I suspect it is rather more like what people are looking for than Journey to the West. => )
And going a bit further away from epic fantasy, Catherynne M. Valente’s Orphan’s Tales duology is a set of intricately nested and intertwined fairy tales drawing on many different traditions, while Barry Hughart’s Bridge of Birds is a very funny and truly wonderful fantasy set in a mythological 7th-century China.
If you like LotR for the way it leaves the reader to infer a great deal, or if you like poetry, try John M. Ford’s collection of short stories, poetry, and essays, From the End of the Twentieth Century. (But if you don’t like Tolkien’s poetry, don’t let that stop you, because I don’t and I positively adore “Troy: The Movie,” among others.)
Finally, if you like LotR for its worldbuilding, try Rosemary Kirsten’s Steerswoman series. It’s not epic fantasy, but when I think of books that give me the joy of uncovering a thoroughly-built and fascinating world, they are the first that come to mind.